Effect of tet methylcytosine dioxygenase 2 on the regulation of transforming growth factor-β1 expression in mesangial cells induced by high glucose / 中华肾脏病杂志

ABSTRACT

Objective To investigate the role of tet methylcytosine dioxygenase 2 (TET2) in the regulation of transforming growth factor-β1 (TGF-β1) expression in human glomerular mesangial cells induced by high glucose.Methods Cultured human glomerular mesangial cells were divided into normal control group (5.5 mmol/L glucose) and high glucose group (30.0 mmol/L glucose) which was cultured for 12 h to 72 h.The gene expression of TET2 in mesangial cells were inhibited by small molecule chemical called SC1,and which were divided into high glucose group (30.0 mmol/L glucose+ DMEM),DMSO group (30.0 mmol/L glucose+0.1％DMSO) and SC1 group (30.0 mmol/L glucose+3 μmol/L SC1).The mRNA and protein expression of TGF-β1,TET1 to 3 and α-smooth muscle actin (α-SMA) was detected by quantitative real-time PCR and Western blotting.Methylation of CpG islands in the regulation region of TGF-β1 was detected by bisulfite sequencing PCR (BSP).The activity of mesangial cell proliferation was assessed by colorimetry of thiazolyl blue (MTT).Results Compared with normal control group,the mRNA and protein expression of TET2 in mesangial cells induced by high glucose was increased significantly in a time-dependent manner (all P ＜ 0.05),but the expression of TET1 and TET3 was not affected.Meanwhile methylation rate of 4 CG sites from 24 h to 72 h were decreased in the first exon of TGF-β1 (P ＜ 0.01),but not in the promoter.Compared with high glucose group,when the expression of TET2 was inhibited by SC1,the methylation rate of TGF-β1 was recovered evidently (P ＜ 0.05),the mRNA and protein expression of TGF-β1 and α-SMA was suppressed,and the proliferation of mesangial cells was decreased (all P ＜ 0.05).Conclusions Demethylation of the CpG island mediated by TET2 may play an important role in the expression of TGF-β1 and mesangial cell phenotype transformation induced by high glucose.